Control system



250-201 AU 252 EX FIP8212 XR 2,151,570 WNER March 21, 1939. D. R. SHOULTS ET AL 2,151,570

CONTROL SYSTEM Original Filed Feb. 27. 1936 2 Sheefis-Sheet l Inventors: David R. Shoults. Harold W. Lord,

Then Attorne l EXAMMER 2 5 0 2 0 1 CROSS REFERENCE March 21, 1939. D. R. SHOULTS El AL CONTROL SYSTEM Original Filed Feb. 27, 1936 2 Sheets-Sheet 2 Inventors:

N m n um w .m t swn m d 3W 2 m D T w reams Man 21, use I 2,151,570

UNITED STATES PATENT OFFICE 8,151.57. OONI'IDL srs'rm navidlnhonltlanlnaroldw. Michelinetady.N.Y.,a-ignorlto(ienaalmtricompanymoorponflonolflewierk Applicatio loll-Ill! 27. 1086. Serial No. .030

Renewed July 20. 1088 19 Chill- (01- I'll-4.6)

Thisinvention relates to control systems, more behin a point on the strip. and positional particularly to register control systems for appaagreement or correct register. ratus having an element operating on a strip of In illustrating the invention in one form therematerial. and it has for an object the provision of of. it is shown as app ie to multi-eolor co ti a simple, accurate, reliable and improved system our web printing apparatus for controlling the of this character. register of successive color printings. It will be One example of an application of apparatus of understood however, that the invention also has this character is found in multi-color continuous application to other industrial apparatus having web printing. In this type of printing, it is somean element ope on 8 strip of m r times necessary to dry the ink of one color before For a better and more complete u r t ndi m the next impression of a different colored ink is of the invention, referenee should w b ha t made. This requires considerable spacing bethe following specification and to the accompanytween the printing units and very often some artiins drawings, of which mm 1 i it si ple dia iicial method of drying. Owing to atmospheric maticai view in perspective of multi-color conchanges and other variable factors, the length of tinuous rotary w b pr n l pparatus. a F 8- web between successive printing units will stretch 2 is a simple dia e-m r p t on 0! or shrink slightly, so that the color imprinted by an embodiment of the invention in a control systhe second printing unit is not in register with teln for maintaining exact res between the the first color, although the apparatus was origisuccessive colored ink impr i pri O nally set up to print the two colors in register a continuous traveling w by h apparatus 01 20 with each other. Generally this variation is not Fig. 1. Referring now to the drawings, a strip of cumulative, but it will tend to vary within certain mate ia t is passed between rolls I 2 c t limits. tuting a printing press unit. These rolls print a For most multi-coior ,work, it is necessary to colored ink design on the strip which is repeated register the colors within plus or minus .01 inch, in s cce nn each revolution f the which is approximately the widthof a very fine rolls. Simultaneously therewith a succession of pencil line. It is, thus, necessary to detect and reference marks or indicia I! are printed in a correct inaccuracies of register of this amount or track near the edze 0f h Strip and in p riess. In order to accomplish this, it is necessary mined relationship longitudinally of the strip with to obtain this same accuracy in timing the operarespect to the designs. It is not necessary that 39 tion of the second printing cylinder that is obthese reference indicia should have any D tained timing the passage of a reference mark or lar relationship w respect to h n I point on the strip. is only necessary that the relationship between In carrying the invention into effect in one 'the reference marks and their associated designs form thereof, a light sensitive device is provided shall be uniform. 35 for producing an electrical impulse in response to In order that the colored ink desis -1 h v the passage of a mark on the strip, and a second sufllcient opportunity to dry before the next color light sensitive device is provided for producing is ap d. considerable n s is p o ded b an electrical impulse in accordance with the potween the printing cyl It end the Pr sition of the element which operates on the strip. ins yh 4. which constitute he n x 40 Means controlled by these impulses are provided Pr in unit- A Shown in F th pac n i for correcting the relationship between the eleproduced by causing the web It to pass underment and strip when the time interval between neath the guide roll it and then upwardly over impulses exceeds a predetermined amount. As guide rolls l1 and ll and again downwardly and 5 long as the time interval between these impulses underneath guide roll it before entering the remains less than this predetermined amount, no printing cylinders H, II of the second unit. A correcting action is initiated. An additional osdiflerent colored ink is impressed on the strip by pect of the invention is the provision of means the printing cylinders ll, l5, and it is necessary for indicating the positional relationship bethat this second printing of a different colored o tween matter or designs printed on the strip ink shall take place in very accurate register with and the element which operates thereon. Indithe design impressed on the strip by the printcations are produced to indicate the conditions ing cylinders II, It. To this end a succession of of positional disagreement in which the operatreference marks or indicia 2| are impressed on log element is ahead of a point on the strip, the strip by the printing cylinders II, it in predepositional disagreement in which the element is termined longitudinal relationship with respect 55 tothecoloredinkdesignsimpressedonthestrip b7 the cylinders II, II. These reiu'ence indicia 2lareillustratedasprintedinatrackalongthe distant edge of the strip.

The printing units II, II and i4, II are driven by any suitable driving means such for example as represented by the electric motor 2i to the drive shaft of which the cylinders are connected through suitable driving connections as illustrated. It will be observed that a diilerential driving device 22 is included in the driving connections between the electric motor 2! and the cylinders l4, It. The input element 22- 02 this dilterential device is provided with worm wheel gear teeth which mesh with a worm member 22, which in turn is driven by a small electric motor 24. when the motor 24 is at rest, the friction oi the worm gearing prevents the input element 22a from turning so that the electric driving motor 2| drives the printing cylinders l4, I! as through a direct driving connection. However, when the electric motor 24 rotates the input element 22. in one direction or the other, the position of the printing cylinders i4, I 5 with respect to the printing cylinders H, i2 is retarded or advanced depending upon the direction of rotation.

In order to detect any inaccuracy in the register of the colors imprinted by the first and second printing units, suitable light-sensitive means are provided for producing electrical impulses in response to the passage of the reference indicia l2 and 20, and these impulses are utilized to control the electric motor 24 to correct the positional relationship of the printing cylinders l4, It with respect to the designs previously impressed on the strip by the printing cylinders ll, i2.

This light sensitive apparatus is illustrated as a scanning unit for responding to the reference indicia l2 and a second scanning unit for respending to the reference indicia 20. The first scanning unit is illustrated as comprising a lamp 2| for illuminating the path of the indicia l2 and a photoelectric cell 28 for responding to the passage of the marks II for producing controlling electric impulses. Similarly. the second scanning unit comprises a lamp 2'! for illmninating the path of the reference indicia 20 and a photoelectric cell 22 for responding to the e of these indicia 20 for producing controlling electrical impulses. These scanning units are so positioned longitudinally with respect to the designs that when the colored ink designs impressed on the strip by the printing cylinders ii, l2 and printing cylinders I4, I! are in correct register, the impulses produced by photoelectric cells 22 and 22 occur substantially simultaneously.

Although the correcting motor 24 may be of any suitable type. it is illustrated as a direct current motor provided with split series field windings 22 and 20. Energization of the motor 24 through one of the field windings causes the motor to rotate in one direction and to produce a corresponding correction in the position of the printing cylinders I4, I! relative to the designs previously printed on the strip, and energization of the motor through the other field winding causes the motor to operate in the opposite direction and likewise to produce a correction in the opposite direction.

As shown in Fig. 2, rectified alternating current is supplied by means of a suitable electric valve 2| through the field winding 29 and armature of motor 24 for rotation of the motor in one direction and similarly rectified alternating eurrent is supplied by means of a similar valve 22 through the field winding 22 and armature of the motor 24 for rotation in the opposite direction. Although the electric valves 2| and 22 may be of any suitable type, they are preferably of the three-electrode type into the envelope of which a small quantity of an inert gas is introduced after exhaust. The presence of this gas within the tube serves to convert the usual pure electronic discharge into an arc stream thereby constituting the tube an electrostatically or grid controlled arc rectifier. The anodes 2| and 22s of the valves 2|, 22 are respectively connected to the terminals of the split field windings 29 and 20 and through these windings to one terminal of the armature of the motor 24 whilst the cathodes Us and 22s are connected through a secondary winding of a supply transformer 23 and an ad- Justable resistance 24 to the opposite terminal of the armature of motor 24. The primary winding of the transformer 22 is connected to a suitable source of alternating voltage represented by the two supply lines 25. Preferably, the valves 2!, 22 are of the hot cathode type and are therefore illustrated as provided with heating elements which are supplied with electrical energy through an intermediate portion of the secondary winding of the supply transformer to which they are connected as illustrated.

Electric valves 2|, 22 when supplied with alternating voltage conduct current only during that half cycle of the alternating voltage in which the anode voltage is positive with respect to the cathode voltage. The discharge is initiated in either of the valves when the voltage of either grid 21s. 22s respectively becomes more positive than a predetermined critical value. Once the discharge has started. the grid is powerless to control the flow of current during the remainder of that half cycle and the current flowing in the anode circuit can only be interrupted by physically interrupting the circuit or by reducing the voltage of the anode to zero with respect to the voltage of the cathode. Thus the current flow is interrupted when the anode voltage passes through zero value at the end of a positive half cycle of applied voltage.

A pair of similar electric valves 26 and 21 are provided for controlling the energization of the valves 2| and 22 respectively. The valves 26 and 21, though similar to the valves 2| and 22, are supplied from a source oi. direct voltage represented by supply lines 22 and 28. As indicated in the drawings, the upper supply line 28 is positive and the lower grounded supply line 29 is negative. Direct voltage for energizing the line 22, 22 may be obtained from any suitable source, such for example as the electric valve rectifying apparatus 40 within the dotted enclosure. This rectifying apparatus is in turn supplied from a suitable source of alternating voltage such as the source 25 to which it is connected through the supply transformer 4i. Inasmuch as this rectifying apparatus per se is standard apparatus sold on the market and does not constitute any part of this invention a detailed description of its structure and operation is omitted. It is sufilolent to understand that it rectifles the alternating voltage supplied from the source 25 and supplies a direct voltage to the lines 22 and 22.

The anodes 26. and 21s of the valves 26 and 21 are connected together by means of two resistances 42 and 42 which as shown are connected in parallel with each other to form a bridge. An

intermediate point of the resistance section 42 is connected to the upper positive supply line 36,

whilst an intermediate point of the lower resistance section 43 is connected through a portion 33. of the secondary winding of the transformer 33 to the cathodes of the valves 3|, 32. The voltage induced in portion 33. of the secondary winding is of such magnitude and phase angle that the valves 3|, 32 are held at cut oil when valves 36, 31 are non-conducting. The grids 3|e. 32 of valves 3|, 32 are respectively connected to opposite bridge points 44, 45 as illustrated.

A pair of voltage dividers are connected across the direct voltage supply lines 36, 38. The first of these voltage dividers comprises a plurality of resistance sections 46, 41 and 48 and the second of these dividers comprises resistance sections 43 and 50.

Preferably, the valves 36, 31 are of the hot cathode type and are illustrated as provided with filamentary cathodes 36s, 31, which are connected in parallel with a portion of the secondary winding of the supply transformer 4| through which energy is received for heating the filaments to the required degree of incandescence. The midpoint of this portion of the secondary winding is connected through conductor 6| to the conductor 62 which constitutes the junction point between the resistance sections 43 and 60 of one of the voltage dividers. It will thus be seen that the cathodes 36s, 31s are normally at a voltage that is negative with respect to the voltage of the anodes 36., 31..

Impulses from the scanning head 26, 26 are amplified by means of a two-stage amplifier 63 and conducted to the grid 31 of the valve 31 and similarly impulses from the scanning head 21, 26 are amplified by means of two-stage amplifier 54 and conducted to the grid 36 of electric valve 36. These two-stage amplifiers are standard devices, well understood by persons skilled in the art and obtainable on the market. They do not in themselves constitute a part of the invention. For this reason a detailed description. of their structure and operation is omitted. It is sufficient to understand that the photoelectric cells 26, 26 are respectively connected to the grids of the valves 65, 66 constituting the first stage of each amplifier respectively and that the anodes of the valves 61, 66 constituting the second stages of these amplifiers are respectively connected to the grids 36c, 31 of the valves 36, 31. The cathodes of all of the valves 66, 66, 61 and 66 are connected to the negative supply line 33 whilst the anodes of the first stage valves 66 and 66 are connected through conductor 63 to the point Is on the voltage divider and the anodes of the second stage tubes 61, 66 are respectively connected through resistances 66 and 6| to the point 46. of the voltage divider, the voltage of which point is more positivethan the voltage of the point To. The voltages applied to the grids of the second stage tubes 51 and 66 are of such a value that both valves are normally conducting, with the result that the points of the resistances 66, 6| to which the grids of the valves 36, 31 are connected are sufliciently negative to hold the valves 36, 31 at cut-oil.

As in the case of the valves 3|, 32, once the valves 36, 31 become conducting, it is no longer possible to control or interrupt the current flow of these valves by the grid voltage. Since the valves 36, 31 are energized from a direct current source, once the current flow is initiated, it will continue indefinitely, unless some special means EXAMINER are provided for physically interrupting the anode circuit or for reducing the voltage of the anode to zero with respect to the cathode voltage. For the purpose of commutating the valves 36, 31 additional electric valve apparatus comprising a half-wave rectifying valve 62 and a full wave rectifying valve 63 are provided.

With the foregoing understanding of the elements and their organization in the completed system, the operation of the system itself will readily be understood from the following detailed description:

Assuming the condition of correct register, 1. e., the printing cylinders I4, I 6 producing an impression on the strip III in correct register with the design previously printed thereon by the first printing unit l2, a reference mark l3 will pass beneath the scanning head 26, 26 simultaneously with the passage of a reference mark 26 beneath the scanning head 21, 26. As a result, simultaneous electrical impulses are produced in the circuit of both photoelectric cells 26, 26. electrical impulses are applied to the grids of the first stage tubes 66, 66 and produce a momentary increase in current flowing through these tubes. This increase in current produces a voltage drop across the resistances 64 and 66 thereby decreasing the magnitude of the positive voltage applied to the grids of the valves 61, 66. In consequence of this decreasing grid voltage, the current flowing through the valves 61, 66 is decreased with the result that the voltage drop across the resistances 66, and 6| is also decreased and the voltage of the grids 31 and 36 which are respectively connected to the negative terminals of these resistances become sufiiciently positive to render the valves 36 and 31 conducting.

The path of the current through the valve 31 is traced from the positive supply line 36 through the left-hand portion of the resistance 42 through valve 31, conductors 6| and 62 and resistance 66 to the negative side of the supply line. Similarly, the path of the current flowing through the valve 36 is traced from the supply line 36 to the right hand portion of the resistance section 42, through the valve 36 and thence through conductors 6|, 62 and resistance 60 to the negative side of the supply source. These currents through the valves 36 and 31 produce a voltage drop through both halves of the resistance 42 thus maintaining the bridge points 44 and 46 at the same relative voltage with respect to each other and with respect to the point of connection of the cathodes to resistance 43. Thus, the voltage relationship between cathodes and grids of valves 3|, 32 remains unchanged and these valves remain non-conducting. Consequently the motor These 24 remains unenergized and no correcting action is initiated.

The current flow through the valves 36 and 31 and through the resistance 56 increases the voltage drop across the resistance 60 so that the upper terminal thereof becomes increasingly positive. A capacitance 66 and a resistance 66. connected in series therewith are connected in parallel with the resistance 66 and one terminal of this capacitance is connected through a portion of the secondary winding of the supply transformer 61 to 'the grid of the electric valve 62. Consequently,

as the upper terminal of the resistance 66 becomes increasingly positive the capacitance 66 which is connected through conductor 68 to the upper terminal 01' the resistance 6!! begins to charge. The plate of the capacitance that is connected to the grid becomes charged with a positive voltage and after a predetermined interval of time, the grid of the valve 62 becomes sufllciently positive to render the valve conducting. As a result current flows in the output circuit of the valve through the primary winding of a transformer '8 which induces a voltage in the secondary winding. when this voltage reaches a sumcient magnitude, the valve 62 breaks down and becomes conducting and current flows from the anode S2. to the cathode and then through conductor 68 and resistance 50 to the negative side of the supply line.

This current momentarily raises the potential of the upper terminal of the resistance iii to a very high positive voltage thereby rendering the cathodes 26s and 21s positive with respect to the anodes which is the same in effect as rendering the voltage of the anodes negative with respect to the cathodes. The result of this is to render the valves 26, 21 non-conducting. By this time, the charge on the upper plate of the condenser it has risen to such a high positive value that it produces a discharge from the anode Nb of the tube 82 to the cathode, thereby allowing the charge to leak off the conductor and leave the system in a reset condition.

If now the length of the strip between the iirst and second printing units should increase for same cause or other, the cylinders I4, I! of the second unit would print late with respect to the design printed on the strip by the first printing unit and thus the color impressed by the second unit would be out of register with the design printed by the first unit. Likewise, the index marking 20 would be late with respect to the corresponding index marking I! so that an electrical impulse would be produced in the circuit of photoelectric cell 20 before the corresponding impulse would be produced in the circuit of the photoelectric cell 22.

This impulse energizes the electric valve, 21, in the manner set forth in the foregoing description, thereby causing the valve 21 to become conducting. The current flow through this valve and the resistance II produces a voltage drop across the resistance I! so that the voltage of the cathode of both valves become increasingly positive. However, the voltage does not become sumciently positive to interrupt the current how of the valve 2! but it does become sufliciently positive to prevent energization of the valve ll by a subsequent impulse transmitted to its grid from the photoelectric cell '28. Consequently, the valve 21 is rendered conducting and the valve 2 is maintained at out off.

The current ilow through the valve 21 lowers the voltage of the left-hand terminal I! of the resistance 42 thereby rendering the voltage of the grid In of the valve 22 increasingly negative. On the other hand, the voltage of the point N at the right-hand terminal of the resistance 42 remains at the same high positive value as the upper line 28 of the supply source because no current is flowing through the valve II. Since the cathodes lit and 22s of both valves are connected to the middle point of the resistance section 42, the voltage of both cathodes is decreased by half the amount of the diiference in voltage between the points 44 and II. This has the same eifect as raising the voltage of the grids of these valves. However, since the voltage of the grid 22 has already been decreased owing to the voltage drop across the left hand section of the resistance 42, the valve 22 is held at cut oil and does not become conducting. The valve ii, on the other hand. since its grid voltage has not been decreased, becomes conducting and passes current from the anode to the cathode through conductor 10, secondary winding of transformer 33, conductor ll, resistance 34, armature of motor 24, field winding 29 and conductor I2 to the anode.

As a result of its energization, the motor 24 rotates the input member 22. of the differential 22 in such a direction as to advance the position of the printing cylinders l4 and I5 relative to the design previously printed thereon by the printing cylinders ll, i2. After a predetermined interval of time determined by the constants of the circuit, the valve 21 is rendered non-conducting in the manner previously set forth in the foregoing description. As a result of the deanergization of the valve 21, the valve 2| likewise is deenergized and ceases supplying current to the motor 2!. The motor 24 then ceases rotating after having advanced the position of the cylinders l4 and il a predetermined amount.

If the inaccuracy in register has not been fully corrected, the foregoing operation will be repeated when the next reference mark I2 passes beneath the scanning head 25, 28.

When the inaccuracy in register becomes less than a predetermined negligible amount, the time interval between the impulses produced in the circuits of the photoelectric cells 26 and will become less than a predetermined value so that for practical purposes, these impulses may be considered as taking place simultaneously. However, the electric valve apparatus is extremely sensitive and would therefore respond to produce a correction even when the interval between impulses is so inilnitestimal as to be of negligible importance. Therefore in order to render the system less sensitive and to eliminate continuous hunting action of the apparatus in seeking to correcting negligible inaccuracies, it is necessary to increase the interval of time between impulses within which both electric valves 28 and 21 'will be energized by the impulses and no correcting action initiated as explained in the foregoing. To this end, a plurality of condensers 18, I4, ll of diflerent capacities are connected so that a desired amount of capacity may be connected in parallel with the resistance ll by means of a selector switch it. The effect of connecting the capacity in parallel with the resistance Ill is to increase the time constant of the circuit of electric valves 28 and 21 and thereby to increase the time interval between impulses in the circuits of the photoelectric cells 2', 22 within which both valves 20 and 31 will be energized in response to the impulses.

If the length of strip between the first and second printing units shrinks, the second printing units I, II will print "early" with respect to the design already printed by printing unit H, H. In consequence, an impulse will be produced in the circuit oi photoelectric cell 22 before the impulse is produced in the circuit of photoelectric cell 28. This will cause the valves 28 and 22 to become energized in a manner identical with that already described for the energization of valves 21 and ii. The valve 22 will pass current to the motor 24 through the other field winding 20, thereby causing the motor 24 to rotate in the opposite direction so as to retard the position of the printing cylinders l4 and II with respect to the design printed by the cylinders ii, l2.

After a predetermined interval of time, the valves 28 and 22 arerendered non-conducting in the previously described manner and the motor 24 comes to rest after having corrected the a i k zooaisasvo CROSS REFERENCE EXAMiNEii position oithe cylinders II and II a predcterwhensaidintervalislcssthansaid-predetermined minedamount. Iitheinaccuracyisnoti'ully correctedthlsactionwillberepeatcdimtilthe impulses produced by reference indicia l8 and I. take place within the predetermined time interval in which both valves 8| and 81 become energized and no further correcting action is initiated. It will thus be apparent that motor 24 provides a visual indication of the positional relationship of the printing cylinder elements it, I and the printed matter on the strip ll, i. e., rotation oi the motor ll in one direction indicates positional disagreement in one direction, rotation of the motor in the opposite direction indicates positional dient in the opposite direction, and the motor at rest indicates correct register.

Although in accordance with the provisions 0! the patent statutes, this invention is described as embodied in concrete form and operating in a specific manner, it will be understood that the elements, apparatus and connections shown and described are merely illustrative and that the invention is not limited thereto since alterations and modifications will readily N88881: themselves to persons skilled in the art without departing from the true spirit of this invention or from the scope of the annexed claims.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Register control apparatus comprising the combination with an element operating on a strip of material, of light sensitive means controlled by the strip for producing an electrical impulse, light sensitive means for producing an electrical impulse in accordance with the position of said element, and means actuated by said impulses for varying the relationship between said strip and element in accordance with the order of occurrence of said impulses.

2. A register control system comprising in combination, an element operating on a strip oi material, light sensitive means controlled by the strip for producing an electrical impulse, light sensitive means responsive to an indication produced on said strip by said element for producing a second electrical impulse and means actusitive devices for introducing a correction in the. relative positions of said strip and element see lectively in a forward or reverse direction depending upon the order of actuation of said dei vices. v

4. A control system comprising iii-combination,

an element operating'on a moving strip of material, a light sensitive device actuated by reference inidicia on the strip, a second light sensitive device actuated by reference indicia produced on the strip in accordance with the operation of said element, means responsive to actuation 01' said devices for introducing a correction in the relative positions of said strip and element when the interval between the actuation of said de-' vices exceeds a predetermined amount, and means for preventing operation oi said corrective means amount.

5. A control system comprising in combination, an element operating on a strip 01' material, a light sensitive device actuated by reference indicia on the strip. a second light sensitive device actuated by reierence indicia placed on said strip in accordance with the operation of said element, means for introducing a correction in the position oi the element relative to the strip it the time interval between said actuations exceeds a predetermined amount and in a direction depending upon the order of actuation of said devices, and means for maintaining said corrective means inactive when the interval be said actuations is less than said predetermined amount.

6. Register control apparatus comprising in combination, an element operating on a strip of material, means for correcting the relative positions of said material and element, an electric valve for controlling said means to produce a correction in one direction, a second electric valve for controlling said means to produce a correction in the opposite direction, a light sensitive device controlled by the strip for energizing said first valve. a light sensitive device actuated in accordance with said element for energizing said second valve, and means controlled by the first of said valves to be energized for preventing actuation of the other of said valves so that the direction of said correction depends upon the order of actuation of said light sensitive devices.

. 'I. Register control apparatus comprising in combination, an element operating on a strip oi material, a light sensitive device actuated by the strip, a second light sensitive device actuated'in accordance with the operation of said element. electric valve apparatus responsive to actuation of said devices and means controlled thereby for producing a correction in the relative positions of said element and strip in a direction dependent upon the order oi actuation of said devices, said valve apparatus serving to continue the correcting action after the actuation of said devices, and additional electric valve apparatus for rendering said first mentioned valve apparatus inactive a predetermined time after actuation oi said light sensitive devices.

8. A control system comprising in combination, an element operating on a strip of material, an electric motor for correcting the position of the element relative to the strip: an electric valve for eflecting operation of said motor in one direction, a second electric valve for effecting operation oi said motor in the reverse direction, a

actuating said first valve, a light sensitive device actuated in accordance with the position of said element for actuating said second valve,- means responsive 'to the actuation of the .flrstoi said valvesto be actuated, for preventing actuation oi the other of said valves when the interval between actuation of said light sensitive devices exceedsa predetermined amount so that the direction or the correcting action of said motor depends'upon the order of actuation of said light sensitive devices.

9. A control system comprising tion with an element operating on a moving strip ing the position of said element relative toasaid strip, a pair or electric valves, a light sensitive device actuated by the strip for actuating one combine-i of material, or an electric motor for correct- I of said valves, a light sensitive device actuated in accordance with the position of said element for actuating the other of said valves, means controlled by the ilrst said valves to be actuated for preventing action of the other oi said valves alter a predetermined interval oi time, and means responsive to actuation of one of said valves for energizing said motor for rotation in a corresponding direction and responsive to actuation of both of said valves for preventing actuation oi said motor.

10. A register controller comprising the combination with an element operating on a strip 01' material, oi an electric motor for correcting the relative positions of said element and strip, a pair of electric valves containing an ionizable medium and supplied from a source oi direct voltage whereby said valve remains active after an energizing impulse. a light sensitive device controlled by the strip for energizing one of said valves, a second light sensitive device actuated in accordance with the position oi said element for energizing the other of said valves, means controlled by the first of said valves to be energized for preventing energisation oi the other of said valves after a predetermined time interval, means responsive to energination oi either of said valves for energizing said motor for rotation in a corresponding direction, and additional electric valve apparatus for deenergizing said electric valves after a predetermined time.

11. A register controller comprising in combination, an element operating on a strip oi material, an electric motor ior correcting the relative positions of said element and strip, a pair of electric valves each containing an ionizable medium and having an anode, cathode and control grid, and supplied from a source of direct voltage whereby it remains active aiter an energizing impulse, a light sensitive device controlled by the strip for energizing one of said valves, a second light sensitive device actuated in accordance with position of said element for energizing the other of said valves, means responsive to energization of one 0! said valves for applying a positive voltage to the cathode of the other of said valves to prevent energization of said other valve when the interval between actuation of said light sensitive devices exceeds a predetermined amount, and means responsive to energization oi either of said valves for actuating said motor for rotation in a corresponding direction and responsive to energize.- tion of both said valves for maintaining said motor inactive.

12.A register control system comprising in terial, a light sensitive device actuated by refercombination, an element operating on a strip of material, an electric motor for correcting the relationship of the element and strip, electric valve apparatus supplied from a source of alternating voltage and having an output circuit connected to said motor and an input control circuit, electric valve apparatus supplied rrom a source of direct voltage and having an input control circuit and an output circuit connected to the input circuit of said alternating voltage valve apparatus, light sensitive means controlled by the relative positions oi said element and strip for energizing said direct voltage valve apparatus whereby said alternating voltage valve apparatus is actuated to energize said motor,.

and additional electric valve apparatus actuated in response to energizatlon oi said direct voltage valve apparatus for deenergizing said direct voltage valve apparatus alter a predetermined interval oi time.

18. A register controller comprising in combination, an element operating on a strip of material, a light sensitive device controlled by the strip for producing an electrical impulse in accordance with the position thereoi, a second light sensitive device for producing an electrical impulse in accordance with the position of said element, means controlled by said impulses for correcting the relationship of said strip and element when the time interval between said impulses exceeds a predetermined amount for correcting the positional relationship oi said strip and element, and means for adjusting the length of said interval.

14. A register controller comprising in combination, an element operating on a strip of material, a pair 01' electric valves, a light sensitive device controlled by the strip to produce an electrical impulse for actuating one of said valves, a second light sensitive device for producing an electrical impulse in accordance with the position oi said element for actuating the other of said valves, means controlled by the actuation of one of said valves for preventing actuation of the other of said valves after a predetermined interval of time, variable condenser means in circuit with said valve apparatus for varying said time interval, and means responsive to actuation of either oi said valves for producing a corresponding correction in the positional relationship oi said element and strip.

15. A control system comprising in combination, an element for performing an operation on a length of material, light sensitive means controlled by said length oi material for producing an electrical impulse, light sensitive means for producing an electrical impulse in accordance with the position 0! said element, and means actuated by said impulses and controlled in accordance with the order of occurrence of said impulses ior indicating the positional relationship of said element and length of material.

18. A control system comprising in combination, an element for performing an operation on a length of material, light sensitive means controlled by said length of material for producing an electrical impulse, light sensitive means for producing an electrical impulse in accordance with the position of said element, and means actuated by said impulses ior indicating the positional disagreement between said element and strip when the interval between said impulses exceeds a predetermined amount.

17. A control system comprising in combination, an element operating on a length of maence indicia on the strip, a second light sensitive device actuated in accordance with the position of said element, means for indicating the positional relationship of said element and length of material it the time interval between saidx of material, an electric valve for controlling said indicating means to produce an indication of positional disagreement of said element and length of material in one direction, a second electric valve for controlling said indicating means to produce an indication of positional disagreement of said element and length of material in the opposite direction, a light sensitive device controlled by said length of material for actuating said first valve, a second light sensitive device controlled in accordance with the position of said element for actuating said second valve, and means controlled by the first of said valves to be actuated for preventing actuation oi the other of said valves, so that the indication of the direction of disagreement depends upon the order of actuation of said light sensitive devices.

19. A control system comprising in combination an element operating on a moving length of material, means for indicating the positional relationship between said element and length of material, a pair of electric valves, a light sensitive device actuated by the length of material for actuating one of said valves, a light sensitive device actuated in accordance with the position of said element for actuating the other of said valves, means controlled by the first of said valves to be actuated for preventing actuation of the other of said valves after a predetermined interval of time and means responsive to actuation of one of said valves for controlling said indicating means to produce an indication of positional disagreement of said element and length of material in a corresponding direction and responsive to actuation of both of said valves for preventing actuation of said indicating means.

DAVID R. SHOULTS. HAROLD w. LORD. 

